Minor fix to silent mode in WinRT
Minor fix to silent mode in WinRT

LucVK/azure-activedirectory-library-for-dotnet,AzureAD/azure-activedirectory-library-for-dotnet,AzureAD/microsoft-authentication-library-for-dotnet,makhdumi/azure-activedirectory-library-for-dotnet,bjartebore/azure-activedirectory-library-for-dotnet,yamamoWorks/azure-activedirectory-library-for-dotnet,AndyZhao/azure-activedirectory-library-for-dotnet,AzureAD/microsoft-authentication-library-for-dotnet,zbrad/azure-activedirectory-library-for-dotnet,AzureAD/microsoft-authentication-library-for-dotnet,AzureAD/microsoft-authentication-library-for-dotnet